Effect of Stimulation of Excitatory Nerve Tract on Release of Glutamic Acid From Olfactory Cortex Slices in Vitro

Thin sections prepared from the olfactory cortex of the guinea pig were incubated in a medium containing [14C]glutamate, and release of radioactive compounds and electrical activity were subsequently examined in the presence of l‐cysteate. The postsynaptic potential was almost completely suppressed in the medium containing l‐cysteate, whereas the presynaptic potential was unaffected. Repetitive stimulation of the excitatory input of the lateral olfactory tract enhanced release of radioactive glutamate. The facilitatory effect of lateral olfactory tract stimulation increased with increase in stimulus frequency and was dependent on calcium. Release of radioactive gluiamine was not enhanced by lateral olfactory tract stimulation. Phenobarbitone sodium markedly depressed both the postsynaptic potential and the effect of lateral olfactory tract stimulation on glutamate release. These results indicate that stimulation to the lateral olfactory tract enhances liberation of glutamate from the tract nerve terminals.